1. Field of the Invention
The present invention relates to a boiler and a low-NOx combustion method.
2. Description of the Related Art
Environmental pollution has long been a serious societal issue, and, also in boilers, there is a demand for a reduction in harmful substances (NOx, CO, soot, etc.). Various harmful substance reducing techniques for boilers have been proposed. For example, a technique is known according to which a cooling member is installed on the downstream side and in the immediate vicinity of the burner (See JP 06-159612 A).
Further, nowadays, in addition to the request to solve environmental pollution, there is a demand for energy saving, etc., and a further reduction in harmful substances is required. That is, to achieve a solution to the problem of environmental pollution and energy saving, there is a demand for a technique to achieve a reduction in harmful substances at a higher level.
More specifically, for energy saving, there is a demand for a boiler capable of realizing a reduction in O2, that is, a reduction in residual oxygen amount in exhaust gas (e.g., a residual oxygen amount of 3% in exhaust gas), a reduction in NOx (e.g., 20 ppm or less), and a reduction in CO (e.g., 50 ppm or less). However, with the conventional techniques, it is rather difficult to realize such a boiler.